The Main Concept Analysis: Validation and sensitivity in differentiating discourse produced by unimpaired English speakers from individuals with aphasia and dementia of Alzheimer type

Abstract

Purpose. Discourse from speakers with dementia and aphasia is associated with comparable but not identical deficits, necessitating appropriate methods to differentiate them. The current study aims to validate the Main Concept Analysis (MCA) to be used for eliciting and quantifying discourse among native typical English speakers and to establish its norm, and investigate the validity and sensitivity of the MCA to compare discourse produced by individuals with fluent aphasia, non-fluent aphasia, or dementia of Alzheimer's type (DAT), and unimpaired elderly. Method. Discourse elicited through a sequential picture description task was collected from 60 unimpaired participants to determine the MCA scoring criteria; 12 speakers with fluent aphasia, 12 with non-fluent aphasia, 13 with DAT, and 20 elderly participants from the healthy group were compared on the finalized MCA. Results. Results of MANOVA revealed significant univariate omnibus effects of speaker group as an independent variable on each main concept index. MCA profiles differed significantly between all participant groups except dementia versus fluent aphasia. Correlations between the MCA performances and the Western Aphasia Battery and Cognitive Linguistic Quick Test were found to be statistically significant among the clinical groups. Conclusions. The MCA was appropriate to be used among native speakers of English. The results also provided further empirical evidence of discourse deficits in aphasia and dementia. Practitioners can use the MCA to evaluate discourse production systemically and objectively.

Key words::

• Aphasia
• assessment
• dementia of the Alzheimer type
• language
• main concept analysis
• oral discourse production

Notes

Acknowledgements

The authors are grateful to all the participants for taking part in this investigation.

Funding: This study was supported in part by the University of Central Florida Office of Research and Commercialization In-house Research Grant (UCF-18709010).

Declaration of interest: The authors report no declarations of interest.

Supplementary material available online

Supplementary Appendix A. Scoring procedures and criteria for main concepts indices in Kong (2009).

Supplementary Appendix B. List of main concepts and acceptable alternative lexical items to be found online at http://informahealthcare.com/doi/abs/10.3109/14015439.2015.1041551

Notes

¹ Pictures used in this study can be obtained from author Kong.

² Four of the subjects in the clinical group of aphasia were unable to finish the whole CLQT assessment. Their scores for this test therefore could not be obtained.

³ The scores for the FLCI could not be obtained from three subjects due to the fact that they could not finish the whole FLCI assessment.

⁴ The final list contains 26 main concepts that were listed by at least 75% (six out of eight) speech therapists who were involved in the validation process.

⁵ For a large sample size with a small standard deviation, one would be confident about the statistically significant effect obtained. In our case, where the sample size for each speaker group was relatively small and the AC and IN had a relatively large standard deviation, the statistical power and results may be compromised. Readers are suggested to interpret the significant group differences found here with caution.

⁶ Based on an aphasia prevalence rate of 0.066% (68).

⁷ Data reported in the 2009 World Alzheimer Report (69). This number is estimated to nearly double every 20 years, to 65.7 million in 2030.